#include <iostream>

int main()
{
	int a, b;
	int lower, higher;
	
	std::cin >> a >> b;
	higher = a > b ? a : b;	
	lower = b > a ? a : b;
	
	int sum = 0; 
	
	while(lower <= higher) 
	{
		sum += lower;
		lower++;
	}
	lower = b > a ? a : b;

	std::cout << "Sum from " << lower
		<< " to " << higher << " is "
		<< sum << std::endl;

	return 0;
}
